21011101221 has 32 divisors (see below), whose sum is σ = 31005711360. Its totient is φ = 12549891200.

The previous prime is 21011101217. The next prime is 21011101231. The reversal of 21011101221 is 12210111012.

It is not a de Polignac number, because 21011101221 - 2² = 21011101217 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21011101197 and 21011101206.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21011101231) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 901906 + ... + 924908.

It is an arithmetic number, because the mean of its divisors is an integer number (968928480).

Almost surely, 2^21011101221 is an apocalyptic number.

It is an amenable number.

21011101221 is a deficient number, since it is larger than the sum of its proper divisors (9994610139).

21011101221 is a wasteful number, since it uses less digits than its factorization.

21011101221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23417.

The product of its (nonzero) digits is 8, while the sum is 12.

Adding to 21011101221 its reverse (12210111012), we get a palindrome (33221212233).

The spelling of 21011101221 in words is "twenty-one billion, eleven million, one hundred one thousand, two hundred twenty-one".